Inter-vivos tubes, when inserted within a patient, are used to provide an air passage to sedated patients, who are unable to autonomously breath. Conventional inter-vivos tubes or endotracheal tubes (ETT) consist of a long hollow tube with an inflatable cuff balloon near the distal end of the long hollow tube. A smaller channel, within the wall of the long hollow tube connects to the inflatable cuff balloon and provides air to the balloon to expand the balloon to engage walls of the patient's trachea. When the cuff balloon is inflated, confirmation of a leak free contact with the trachea is determined, and delivery of anesthetic gases and oxygen then proceeds.
In the conventional inter-vivos tubes, the tubes are extended past the vocal cords so that a distal end of the inter-vivos tube is contained within the trachea passage. The balloon element (i.e., a cuff), located at or near a distal end of the inter-vivos (i.e., a distal cuff) tube is then expanded to prevent air (or gas) administered through the inter-vivos tube from escaping upward toward the mouth while the administered air (or gas) is directed directly toward the sedated patient's lungs.
Conventional ETT vary in size and are numbered according to the internal diameter (ID). In children the internal diameter varies from 3.5 to 7 mm and in adults from 7-11 mm. Ideally the ETT diameter should approximate closely the glottic size of the patient as the tube must past through the vocal cords to allow the cuff balloon to expand toward the trachea walls.
However, as there is no way to estimate the glottic size (or vocal cord size) prior to intubation, an ETT selected for a patient is determined based on the sex, height, and weight of the patient and the experience of the person inserting the ETT into the patient. The distal inflatable cuff incorporated into present day ETTs compensate for any mis-sizing of a selected ETT by compressing the tracheal wall to establish a closed circuit inflow from the anesthesia machine and outflow from the patient's lungs to the exhalation value.
However, if the circumference of the selected ETT is too small then the flow of air or gas to patient is restricted. That is, the smaller circumference of the ETT, in relation to the size of the glottis, creates increased gas flow resistance, especially when the patient is ventilating spontaneously. This resistance is in a range from 35 to 100 percent. In pediatric procedures, where a cuffed tube is particularly undesirable and to avoid pressure on the vasculature of a particularly delicate tracheal wall, a “Cole” funnel shaped tube is often used to create an air leak-free flow.
In addition, it is known in the medical art that the endotracheal tube cuff contacting the trachea may result in damage to the patient's trachea as the cuff presses against delicate tissues within the trachea walls.
Some of the drawbacks of present day ETTs are the necessity of constructing a longer endotracheal tube that has to extend well into the trachea with an expandable distal cuff that compresses against the tracheal wall. The ischemic compression of tracheal wall capillaries, caused by the expanded distal cuff, often results in the well-documented inflammation of the tracheal wall and diminished capillary activity.
In addition, conventional cuffed ETTs often contribute to the well-known problem of Ventilator Associated Pneumonia (VAT) that is generally attributable to the inflated cuff contacting the trachea and complicating post-operative recovery. The occurrence of VAT in patients increases the cost associated with surgery.
Hence, there is a need in the industry an expandable inter-vivos tube that overcomes the drawbacks occurring with the use of conventional inter-vivos (endotracheal) tube design.